Here are some guidelines to exposure compensation in reflected metering

They might be useless to old hands but I hope they’ll be useful for the less experienced participants.

Some examples of things to be considered like 18% gray in true life, hence no compensation necessary:

Green fields and trees

Brown earth

Fall foliage

Blue sky

Sun tanned faces

Typical exposure compensation for some subjects in f-stop values

Fog: OPEN 1 stop

Sand: OPEN 1.5 stops

Snow: OPEN 1.5 to 2 stops

White flesh tone: OPEN 1 stop

Palm of hand: OPEN 1 stop

Overcast sky: OPEN 2 stops

Blackboard: CLOSE 2 stops

Black flesh tones: CLOSE 1.5 to 2 stops

Remember in any case things lighter than 18% gray will need to OPEN the aperture (or slow down the speed) to be properly rendered and conversely things darker than 18% gray will need to CLOSE the aperture (or increase speed). Lighter things to be rendered lighter than the 18% gray need to be exposed MORE than the reading and darker things need to be exposed LESS than 18% gray to be rendered darker.

Friendly

François P. WEILL

-- François P. WEILL (frpawe@wanadoo.fr), May 17, 2002

Answers

Hi Francois Dont you mean OPEN 1.5 - 20 stops for black skin tones??

-- Karl Yik (karl.yik@dk.com), May 17, 2002.

He doesn't.

When measuring the skin tone, the camaera will try to make it 18% grey. As the skin is darker, you need to under-expose and thus close.

For kaukasian skin the recommendation I heard was 0.5 stop, but it will probably vary depending on the person

-- Reinier (rvlaam@xs4all.nl), May 17, 2002.

A weathered (not newly finished) asphalt pavement will give a good 18% reading, too, in a pinch. Blue sky is good, if at least 90 degrees away from the sun.

-- Bob Fleischman (RFXMAIL@prodigy.net), May 17, 2002.

Thanks Francois - useful information.

As a rule I am generally pretty suspicious of reflected meter readings and whenever possible use incident readings. My, quite literally off the 'cuff technique', is to use the back of my hand as reference - in my case it seems to match my M6's meter pretty accurately for 18% grey. Providing my hand is catching the same light as my subject it works very well, even with exposure accuracy- sensitive films light Velvia. I do the odd calibration with a handheld meter, to take account of tanning in the summer, but the variation seems minimal.

The only drawback is you end up looking rather eccentric pointing a camera at your hand, but then M users coud never be accused of pandering to convention.

-- Matt Pulzer (matt@pulzer.org), May 17, 2002.

When shooting hockey I open up my lens about 1 stop... (ie one more stop of exposure)... On an manual camera I set my asa to 400 for asa 800 film...

-- Kelly Flanigan (zorki3c@netscape.net), May 17, 2002.

IMHO, reflected light readings, if used properly, are far more reliable than incident readings. the film, of course, only cares about the reflected light. by taking a reflectance reading at the camera, you are measuring what the film will see. interpreting incident readings requires the photog to make assumptions about tone and surface reflectance that may or may not be accurate. it is an INDIRECT way of measuring what the camera will see. as long as you understand that a reflected reading is giving you correct exposure for the measured area so as to render on film as middle grey, you shouldn't have any problem. learn your zones, learn the size of your meter area, and you can create any value you want on the neg. indeed, with a true 1 degree spot and a rudimentary knowledge of zone values, you can know with absolute certainty how your scene will render on film. incident readings, by contrast, require you to make lots of assumptions about how your subject will reflect the lite. having said all that, if you are shooting a typical scene that IS 18% reflectance, both systems will work about equally well -- and the incident reading is less likely to get fooled by backliting.

-- roger michel (michel@techfoundation.org), May 17, 2002.

Matt:

That’s an old trick, mainly useful in backlit situations …

And a useful one as long as your skin tone approximate the famed 18% reflectance…

I don’t care for the drawback you mentioned, efficiency is what I care for :)))).

Roger:

Sorry but the reflective method has two main advantages: much easier when using tele-lenses far from the subject, much more prone to creative interpretation… But certainly not accuracy as far as a scientific approach is used. The “objective” metering is always the incident one as it averages the light FALLING on the subject and so is independent from the reflectance of the subject… This is not merely my opinion but what has been demonstrated long ago. Notice incident reading is ever used for illuminance (LUX) metering.

What is true in your theory is more than often interpretative reflective metering will end up with a much better shot than the direct application of incident meter reading…

Friendly.

François P. WEILL

-- François P. WEILL (frpawe@wanadoo.fr), May 17, 2002.

FPW -- i guess we'll have to agree to disagree about this. while the incident reading certainly yields an objective measurement of the lite falling on the subject (at least if you can approach the subject -- as you point out, you often can't approach the scene in a landscape shot at infinity), to figure out how that incident lite will bounce off the subject and record on the film absolutely requires SUBJECTIVE assumptions about the tone and reflectance of your subject. only a reflected reading will tell you what the film is actually seeing. all you have to do then is decided how many zones above or below medium grey you want your subject to appear on the film. very direct, very objective, very easy.

-- roger michel (michel@techfoundation.org), May 17, 2002.

snore........

-- phil the small (ask@asd.org), May 17, 2002.

Roger -

I'd have to gently disagree with you on the landscape bit. If there are clouds that diffuse the sunlight on what you're trying to shoot, and your incident meter reading is taken in bright sunlight, you're absolutely correct; however, if the landscape scene is well-lit by the same sun that is illuminating you, an incident reading will do the trick.

-- George C. Berger (gberger@his.com), May 17, 2002.